My son is in the 9th grade and has been playing soccer since he was four. Right now he plays for his high school soccer team, as well as for a club/travel team, and he plays on his own almost daily. He burns a lot of calories and needs a lot of energy to keep playing soccer as much as he does. He has also been a vegetarian since birth.
I wanted to share what it is that I make him to eat before games or between games when we are at a tournament (you play a couple of games in a day at tournaments). One of his favorite pre-game or in between game fuel sources is a Subway veggie sub. He loves them! He gets a footlong and he has it loaded with veggies. He gets everything except for jalepenos and olives.
Other things that I make for him include such options as fruit bowls, bagels, and acai bowls. If it's a game after school (so he's had lunch, but it's before dinner), I will make him a little plate of fresh fruit and some nuts. I also offer him some granola bars. But this is pre-game fuel for my athlete. Lots of fresh fruit, a little bit of nuts or a bagel, or a veggie sub. It just depends on when the game is during the day. Fruit is great for giving him energy and as a recovery food, then I'm sure to throw in a little protein so that it carries him longer.
This works great for him. If you are wondering what to give your athletic kid before or between games, consider foods like these. I'll add in a few pictures of things I've given him before or between games.